Ontogeny and LTH increase the full width at half maximum (FWHM) amplitude for Ca2+ sparks. A–F: histograms of Ca2+ spark FWHM for SparkMaster analyses of recordings made from fetal, newborn, and adult sheep pulmonary arterial myocytes housed in normoxic or long-term hypoxic conditions. G: bars are for fetal, newborn, and adult normoxic (open) and long-term hypoxic (solid) conditions. *P < 0.05 and ***,†††P < 0.001 denote significant difference within (*) groups based on their age using a Kruskal-Wallis 1-way ANOVA on ranks with a Dunn's multiple comparison test and between (†) groups based on their altitude using a Mann-Whitney U-test.